Enzymes have become well known for their catalytic role in many biological functions. In general, catalysts lower the energy of activation required for a chemical reaction to proceed, thereby facilitating the start of a reaction, as well as enhancing the reaction's speed and efficiency. Often, these factors of speed and efficiency may dictate the biological value of a chemical reaction, and produce varying physiological results.
One of the most common reactions which enzymes catalyze is the hydrolysis, or digestion, of various nutrients such as proteins, lipids, and carbohydrates into smaller constituents. Such digestion is required in order for most organisms to utilize these substances in carrying on essential metabolic functions. Other chemical reactions involved in metabolic function, such as the production of ATP and gene reproduction, are also highly dependent on various enzymes.
Enzymes may be isolated or derived from a variety of sources, including animal tissue and products, fungi, bacteria, and plants. One example is the digestive enzyme pepsin, which was first isolated from the stomach and intestinal lining of pigs. Other examples of digestive enzymes include papian, which is derived from papaya plant, and bromelain, which is derived from pineapple.
Some enzymes are independently capable of asserting a catalytic effect. Other enzymes may not achieve catalytic activity without the presence of a second substance, or cofactor. Still other enzymes may be capable of asserting a catalytic effect without a cofactor, but have their potency and efficiency enhanced when the proper cofactor is present. Other variables, such as conditions of the physiologic environment, may also affect the catalytic activity of an enzyme. For example, many enzymes show little activity at a low pH, but become increasingly active as pH rises.
Environment not only affects the activity of many enzymes, but may also affect their stability. Harsh or extreme, physiologic conditions may destabilize many enzymes to the point that they lose their chemical and structural integrity and become incapable of exerting a catalytic effect. For example, both bromelain and papian display low tolerance for the pH extremes of the human digestive system. As such, when ingested orally, bromelain and papian lose much of their ability to aid in the digestion of food and attendant absorption of nutrients. In fact many enzymes experience such degradation when subjected to the environment of the stomach.